L17 - Marine mammals Flashcards
What are marine mammals?
Heterotrophic - consumers, homeothermic - maintain constant body temp independent of ambient temperature. Endotherm (as all mammals) - warm-blooded animal creating heat internally, air breathing - have lungs, exchange gasses directly with the atmosphere. Viviparous - give birth to live young, have hair or fur. Nurse young with milk (have mammary glands), live partly or fully in marine/aquatic environment. K-selected species (populations fluctuate at or near carrying capacity (K)), stable pops, low offspring, long gestation, slow maturation, extended parental care and long life spans
Where in the world?
From extremely large to very small ranges
What are mammals and sharks? Endo or ectotherms?
Endotherms - mammals (115 spp)
Ectotherms - sharks (242 spp)
What is the taxonomic groups of Cetaceans?
Order Artiodactyla, even toed ungulates) the whales, porpoises, and dolphins
What is the taxonomic groups of Pinnipeds?
Order Carnivora, seals, sea lions, walruses. They use flippers to move both on land and in the water.
What is the taxonomic groups of Sirenians?
Order - Afrotheria, Paenungulata, manatees and dugongs
What is the taxonomic groups of marine fissipeds?
Order carnivora, sea otters and polar bears.
What are the Cetaceans?
Whales, dolphins, porpoises. Baleen whales (mysticetes) and toothed whales (odontocetes). Planktivores, piscivores, and carnivores. They spend their lives in water and have many adaptations to their entirely aquatic lifestyle. There are over 90 different species of cetacean from the smallest Hector’s dolphin and the Vaquita (1.2m) to the blue whale (nearly 30m and 199 tonnes).
What are the Cetaceans? pt2
Approx 28 species recorded in the Uk, and wales has four common regularly sighted cetaceans and another four regularly see but not as common. Unusual species strandings also happen from time to time. Planktivores, piscivores and carnivores with variety of feeding tactics and techniques: lung feeding, bubble netting, shore chasing, jumping in and out of trawler nets, tail slapping, and giant stunning clicks of the spermwhale.
What are Mysticeti?
13 spp, filterfeeders: baleen traps krill or bait fish, water is forced back out of the mouth. Ex. Blue, fin, grey, humpback, minke whales
How is there iron nutrient cycling?
Whale poop to phytoplankton conveyor belt in the water column for nutrient cycling (iron). Recovering baleen whale populations may also increase phytoplankton may also increase CO2 sequestration in oceans.
What are Odontoceti?
> 70spp. Simple, peg-like teeth, considerable variation between species; adapted for grasping and tearing, not chewing. Diet: fishes, squids, bottom invertebrates. Include dolphins, porpoises, belugas, narwhals, sperm, orcas, river dolphins, and beaked whales
What are Pinnipeds?
36 extant species, 50+ extinct. Pinnipedia means ‘fin-footed’. Spend the majority of their lives swimming and feeding in water. Come onto land or ice flows to give birth to young, rest, and moult. Include - true seals (Phocidae), eared eals: sea lions and fur seals (Otariidae) and walrus (Odobenidae)
What is the features of sea lions and fur seals?
external ear, long neck, external testicles in males, posterior flippers can be moved forward, anterior flippers used in swimming. Anterior flippers rotate backward to support weight and keep head erect; undersurface and edge not covered with hair or nails to reduce water resistance in swimming
What is the features of seals?
Short neck, no external ear, anterior flippers covered with hair, five toes with sharp nails; they cannot be rotated backward. No external tescticles in males, use posterior flippers in swimming; they cannot be moved forward.
What are sirenians?
Manatees (trichechidae) and the dugong (dugongidae). Spend their whole lives in water. The only entirely herbivorous group of marine mammals. All four species endangered or threatened, particularly dugong.
What are Sea otters (Enhydra lutris)?
Fully aquatic. Adult sea otters may eat as much as 9kg of food each day: sea urchins, crabs, abalone, clams, mussels, octopuses, and fish. Also the marine otter (Lontra felina) a small species found in south america, which lives in coastal areas is considred by some to be a type of sea otter but they spend considerably more time on land.
What are Polar bear (Ursus maritimus)?
Polar bear - the largest land carnivore, specialised adaptations to Arctic and marine environment. Adult polar bears need an average of 2kg of fat per day to maintain their weight; diet includes mostly ringed and bearded seals but also other seal species, walrus, narwhal, beluga whale, whale carcasses, fish, birds, eggs, berries, and kelp
What are the ecological functions?
Marine mammals represent a variety of ecological roles, including herbivores (manatees), filter feeders (baleen whales), piscivores (dolphins and porpoises) and top predators (orca and polar bear) who predate on other marine mammals. Transfer of nutrients (downward via death, upward via defaecation in euphotic zone). Community structure - sea otters predate on urchins - kelp forest develop; dugong grazing increases seagrass productivity (germination rates improved if eaten by dugongs). Benthic habitat modifiers - sediment turnover created by a walrus feeding promotes early colonisers (amphipods).
What are trophic niches & ecosystem changes?
Marine mammals span the full range of ecosystem macrofauna, from obligate planktivores to apex carnivores. They include sympagic (solid ice), pelagic, benthic and deep-sea feeding species, representing low/mid and high trophic levels. MacKenzie et al, 2022, empirically defined the trophic function, nutrient sources and degree of specialisation of marine mammals feeding in the arctic waters around svalbard. Strong niche partitioning and little between species functional redundancy. Each species fills a distinct niche. So loss of any of these species can lead to ecosystem-scale effects and reciprocally, changes in these vulnerable ecosystems could result in reduction or loss of these species in the european arctic.
What is marine mammal evolution?
Back to the sea after 300 million years. Each taxonomic marine mammal group evolved from a different group of land mammals, whose ancestors separately ventured back into the ocean environment. Despite these different origins, many marine mammals evolved similar features - streamlined bodies, paddle-like limbs and tails. Through convergent evolution.
What is marine mammal convergent evolution?
The independent development of similar traits or features (as of body structure or behaviour) in unrelated or distant related species or lineages that typically occupy similar environments or ecological niches. The fossil record demonstrates that mammals re-entered the marine realm on at least seven separate occasions. Five of these clades are still extant.
What are the challenges of living in the aquatic enviro?
Breathing, regulating body t, relative weightlessness, movement, diving, communication, sound underwater, low-light enviro, sleeping, mating/nursing.
What are respiratory adaptations: breathing?
Adaptations to skeletal structure and locomotion. Streamlining, legs into paddles or fins for steerage, loss of hindlegs (cetaceans and sirenians), skin and blubber reducing drag, loss of external appendices (ears, genitalia). Large powerful tail fluke for efficient propulsion. Paired flipper movement in pinnipeds (and sea otter). Dorsoventral undulation in cetaceans and sirenians. Wave riding and porpoising reduces cost of transport. Dorsal fin for rotational stability. No need for pelvic bones to carry body weight-vestigal pelvis bones remain.
What are diving adaptations - resistance?
Resistance - streamlined body shape to reduce drag: paddle shaped fore limbs, vestigial hind limbs (within body wall), no external digits or ears, hairless, internal reproductive organs
What are diving adaptations - Water conservation?
Use water in food and inspired air, specialised kidneys.
What are diving adaptations - Sensory adaptations?
Specialised hearing ability, specialised vocal production, specialised adaptable lenses for vision in both air and water (seals). Whales produce low frequency sounds which can travel for hundreds of kilometers, dolphins and porpoises have evolved ability to produce and process echolocation signals to navigate and forage even in dark, murky waters.
What are diving adaptations - Thermoregulation?
Large body with small surface to volume ratio to reduce heatloss, subcutaneous blubber layer (or dense hair) for insulation, counter-current heat exchange in extremities to conserve and dissipate heat
What are diving adaptations - Pressure and O2?
Collapsible lungs to force air into tissues to reduce bends, minimised airspaces, exchange 90% lung gases in each breath, external nares on top of head, reinforced airway, high red cell count (more blood volume), oxygen storage in muscles (myoglobin), high tolerance to lactic acid and CO2, apneustic breathing, bradycardia, reduced blood flow to extremities.
What is echolocation in odontocetes?
Echolocation evolved separately in dolphins and in bats => convergent evolution. All odontocentes echolocate. High freq, very short duration, directional pulsed sounds, ‘clicks’ - returning echoes used for navigating and foraging (SONAR). Can distinguish very small objects: stationary, moving, size, dimension, density, direction. Airways separate from food intake, and form part of complex structure of phonic lips and melon in odontocetes enabling echolocation. Harbour porpoise smallest cetacean species in UK.
Studying marine mammals - acoustics?
We can study acoustic comms/ acoustic behaviour. Function of vocalisation. How sounds produced, studying animals using the sounds they produce
What are acoustic methods?
Passive/active, static/mobile (towed, floating). Hydrophones, sonobuoys. DAT recorders/laptops sound cards, DAQ system. Click loggers: C-PODs, F-PODs. Soundtraps, animal attached tags.
What happens in swansea bay monitoring?
Marine mammal monitoring in Swansea Bay for the tidal lagoon swansea bay project - mooring trials. C-PODs deployed in strategic locations to allow impact monitoring and long-term acoustic dataset. Identification of potential hazards to moored devices in swansea bay - acoustic release trial. Designing the most appropriate mooring set up to withstand the harsh environmental conditions in swansea bay. Examining habitat use of harbour porpoise at 5 different locations around the proposed lagoon
What has happened in Swansea Bay research?
Baseline data collected for 1 year. Assessed best method for mooring and deployment, both dolphins and porpoise frequent the area porpoise detections on 85% of days detected. Examined harbour porpoise habitat use with relation to diel, tidal and seasonal patterns. Diel patterns were similar to those found in cardigan bay but tidal pattern of area use differs. There was no equally clear winter/summer distinction on habitat use although there was an increase of HP detections in the autumn and winter.
What has happened in Swansea Bay research - results?
Seasonal diel and tidal variations. Differences between dolphins and porpoises. Mitigation against impacts of tidal energy development - look for times when disturbance might be less likely.
What was found in cetacean DNA capture?
Genetic pop studies in the UK non existent as live biopsy sampling problematic. Most data from stranded animals with obvious issues and biases. Genetic material captured in large whales. Attempt to capture from bow-riding common and bottlenose dolphins. Three different vessels, 13 samples with DNA - 1 successful sample with dolphin DNA. Issues with capture (bigger petridishes needed), storage, transport, and process, primer design.
What are there concerns about?
Conservation concerns : legacy of whaling: current and historic. Noise, seismic exploration, military sonar, shipping, entanglement, by catch, over-exploitation of fisheries.
What is the problem with Pollution?
Plastics, persistent organic pollutants and heavy metals in our ocean and our waterways: entanglement, ingestion, lack of nutrition, immune system and illness. Some chemicals like polychlorinated biphenyls (PCBs), a by product of the plastic industry for very long time and can affect reproduction and resistance to disease.
PCBs in stranded cetaceans?
Reproductive failures: disturbances gestation, loss of calves, lack resistance to diseases. Shortened life span, general habitat degradation.
What are the problems associated with global climate change?
Warming, increasing atm CO2.
What are the problems associated with Physical changes in oceans?
Increased continental freshwater discharge, increased water t/ thermal expansion. Sea ice loss, altered circulation, acidification.
What are the problems associated with Abiotic/biotic consequences?
Altered predator/prey/pathogen/vector/toxin distribution & abundance. Shift in location of suitable thermal habitat, sea-level rise, altered storm frequency/intensity
What are the problems associated with Manifestations of effects on marine mammals?
Altered foraging behaviour/success, altered predation/ disease/ toxin exposure, loss of pinniped pupping habitat, loss of access to foraging habitat, altered mammal distribution, altered distribution of fishing operations/ vessel traffic
What are the problems associated with population-level consequences for marine mammals?
Reproductive success, health, natural mortality, human-cause mortality
